PATCH /crm/objects/2026-03/contacts/{contactId}

Update an existing contact, identified by ID or email/unique property value. To identify a contact by ID, include the ID in the request URL path. To identify a contact by their email or other unique property, include the email/property value in the request URL path, and add the idProperty query parameter (/crm/v3/objects/contacts/jon@website.com?idProperty=email). Provided property values will be overwritten. Read-only and non-existent properties will result in an error. Properties values can be cleared by passing an empty string.